Electric control device



H. E. HELLER ETAL ELECTRIC CONTROL DEVICE June 2, 1959 Filed Deo. 2 4,1956 4 Sheets-Sheet 1 roy, Y et z m5? TeKK MH R w55 F o 1 uf JL wwf 6dra una H207 v. a F

June 2, 1959 H. E. HELLER ET AL ELECTRIC CONTROL DEVICE sheets-shevzFiled Dec. 24. 1956 Fmi. 2

vJune 2,l 1959 H. E. HELLER ETAL 2,839,426

ELECTRIC CONTROL DEVICE f Filled nec. 2-4. 195s 4 sheets-sheet a June 2,1959 'H. E. HELLER ET AL ELECTRIC CONTROL DEVICE 4 Sheets-Sheet 4 FiledDec. 24, 1956 Heller #22950 l u Teodvre F, Bruyn? INVENTORS Helder! 'fE, Zadel/n clarence r o R N E Y United States Patent. C

ELECTRIC CONTROL DEVICE Herbert E. Heller, Wauwatosa, Wis., Rudolph E.Kelto, Munising, Mich., and Clarence W. Kuhn, Wauwatosa, and Theodore F.Rosing, Whitefish Bay, Wis., assignors to Cutler-Hammer, Inc.,Milwaukee, Wis., a corporalion of Delaware Application December 24,1956, Serial No. 630,417

3 Claims. (Cl. 200--104) This invention relates generally to electriccontrol devices and more particularly to electromagnetically actuatedswitches which are suitable for use as contactors or relays.

It is an object of this invention to provide an electric control devicewith high performance characteristics which is more economical tomanufacture than prior art devices.

A still further object is to provide a switch of this type havingmovable bridging contacts, operating plungers and compression springswhich are quickly and easily assembled and disassembled.

The coil of the electromagnet may be loosely mounted between the magnetframe and the movable armature With the return springs placed to reactbetween it and the movable armature. This also helps in establishingproper flush contact between magnet frame and movable armature andpermits easy assembly and disassembly.

The compression spring for the movable contact assembly is held in placeon the operating plunger by a cup member which slides over the end ofsuch plunger and is rotated to locked position and there held by theforce of the spring. Disassembly is accomplished by overcoming thefrictional lock created by the spring and rotating the cup to unlockedposition.

A switch having these characteristics is hereinafter described and shownin detail in the drawings, in which:

Fig. l is a view in front elevation of a switch embodying the inventionwith parts broken away and shown in section;

Fig. 2 is a sectional view taken on line 2-2 of Fig. l, showing theelectromagnet de-energized and the switch open;

Fig. 3 is a sectional view also taken on line 2-2 of Fig. l and showingthe electromagnet energized and the switch closed;

Fig. 4 is a sectional view taken on line @-4 of Fig. l;

Fig. 5 is a perspective view of the movable armature and adjustablelinkage;

Fig. 6 is a bottom View of such armature;

Fig. 7 is a fragmentary sectional View taken on line 7-7 of Fig. 2; and

Fig. 8 is a fragmentary sectional view taken on line 8-8 of Fig. 7.

The switch shown in the drawings is designed for handling up to 20amperes at 250 volts A.C. with three poles. The rating of the Iswitchmay be varied and it may be furnished in 2, 3 or 4 pole versions withinthe scope of this invention. The induction coil is generally designedfor 24 volts at 60 cycles AC. The elements of the switch are containedwithin or mounted on an insulating housing 1d, the novel characteristicsof which will be described in detail in connection with the descriptionof the switch elements. This housing has many characteristics well knownto those skilled in this art which are designed to prevent `voltageleakage and dash-over and provide for proper heat dissipation and thelike. These will not be described in detail except where not apparent.When ICC the switch is fully assembled, a mounting plate 12 is securedto the rear of the housing to hold the parts in place and provide meansfor mounting the switch to a panel in the position shown in Fig. l.

The contact assemblies of each pole are mounted on the outside of adividing wall 13 between sides 14 and are separated by partitions 16.Each such contact assembly includes a pair of fixed contacts 1d and 2liand a bridging contactor 22. All contacts include silver compositioncontacting portions mounted in a standard manner. The fixed contacts 20may have additional offset extensions with terminal screws. All of thexed contacts are lo-` cated by interfitting tongue and grooves indicatedat 24 and are rigidly secured by screws 26 threadedly engaged withinserts molded into the housing at appropriate places. These screws mayalso act as terminal screws. The bridging contacter 22 is part of amovable contactor assembly which consists oi a lat insulating plunger28, the bridging contactor 22, a compression spring 30 and a locking cup32. The plunger is narrowed to form shoulders 34 at the base of atongue. The contactor 22, being provided with a rectangular shapedopening, loosely rides on such tongue and is resiliently urged againstsuch shoulders by the compression spring. The spring and contactor areremovably held on such tongue by the locking cup 32. The locking cup hasa noncircular opening 36 adapted in one position to slide on to thetongue. However, when the cup is rotated the sides of suc'n opening willenter indentations 3S in the tongue and hold the cup on the tongue withthe spring under compression. To make sure that the cup will not rotatefrom the locked position during normal operation, the cup may havedepressions 40 into which the edge of the indentations 38 seat. However,the cup may be unlocked by forcibly rotating it until the non-circularopening aligns with the tongue. The insulating plungers 2.55 areslidably mounted in rectangular openings 42 on the dividing wall i3 andtheir inner ends project to the rear lside of such wall and have smallopenings 44 by which they are connected to the electromagnetic operatingmeans as hereinafter described` An enclosed pocket d5 for each of thecontact assemblies is completed and closed by a cover 46 having sides 48which snugly lit between adjacent ones of the sides ld and partitions16; the ends of the sides 48 resting on the iixed contacts 18 and 20 tohold the contacts in place when screws 26 are loosened. The sides 48have slots d@ which accommodate the reduced sections of the partitions16 between the grooves 24. This creates a cornered or tortuous pathbetween adjacent pockets. These pockets confine any ionization due toarcing and thus increase the resistance to short circuiting.

The electromagnetic means for operating the contact assemblies is on theinner side of the dividing wall 13 between the sides 14; there beingprotecting walls 50 ex tending between the sides 14 to form a recess inwhich part of such means is located. The electromagnetic means consistsof a movable armature 52, an induction coil 54, and a magnet frame 56.

The movable armature S2 is loosely slidably mounted between guides 58extending from the protecting walls Si?, the upper one of which isnotched at 60 to facilitate assembly. In comparison which the magnetframe 56, the movable armature has much greater mass. It has threespaced legs 62 which are as long as the coil S4 with the center legoperating within the central opening of the coil. The outer (toward theright as viewed in Figs. 2 and 3) stroke of the movable armature islimited by engaging projections 64 on the dividing wall 13. Its inner orcontact closing stroke is limited by engaging the magnet frame 56. As isstandard practice shading coils 65 may be employed on the armature 52.

The induction coil 54 is Wound bobbin style on a molded insulating frame66 having an open core loosely receiving the center one of legs 62, aninner end plate 68 and an outer end plate 69 having spring centeringprojections 70. The coil is loosely mounted with its outer end plate 69within and laterally guided by the protecting walls 50 and guides 58 atthe ends thereof. Projections 72 formed between the protective walls 50and guides 5S have ends which engage the end plate 69 to limit its outermovement. The coil is held on the seat thus formed by magnet frame 56engaging the end plate 68 and can move slightly in all directions toadjust for variable manufacturing dimensions and to prevent anyfrictional locking between the movable armature and such coil. The coilhas leads 73 which are secured to conveniently placed terminals. Thewindings of the coil are not enclosed by any .part of the housing andfree circulation of air thereabout is obtained to dissipate the heat ofthe coil.

The magnet frame 56 has its ends positioned in recesses 74 formed in thesides 14 and seats against convexly curved bottoms 76 (see Fig. 3) whenthe electromagnet is energized. This permits the magnet frame to rockand establish a flat surface to surface engagement with ends of thearmature legs 62 to eliminate chattering and other objectionable noiseand the necessity of maintaining costly close tolerances in manufacture.

It has been found preferable to resiliently return the armature 52 toswitch open position and thus permit the switch to be used in anyposition. This is accomplished by coiled compression springs 78 seatedon the spring centering projections 70 and on brackets 80 attached tothe armature, such brackets also having spring centering projection 32.The springs 78 are within the protecting walls 50 and at times may beguided thereby. Springs 7S are so selected that upon de-energization ofcoil 54 they will overcome inertia and friction of the armature andcontact assemblies and move the latter to open circuit positions.

The contact assemblies are each connected to the movable armature 52 byan adjustable linkage which allows each contact assembly to beindependently adjusted. Each contact assembly has its spring 3) whichwill be compressed after the bridging contactor 22 engages the fixedcontacts 18 and 2t) as the movable armature 52 moves into face contactwith the magnet frame 56. As the silver composition contacting portionswear, good contact will still be obtained by the action of the springs30 allowing the necessary overtravel to provide such wear allowance (say.053 to .O59 inch). Since it is good practice to have contact pressuresin the neighborhood of 7% oz. to 8% oz., it requires considerable forcefrom the electromagnetic operating means to compress such springs priorto the closing of the magnetic gap. lf the wear allowance range ismaintained with close tolerance the electromagnetic force is lessenedand smaller coil capacity is required. To provide for such small wearallowance range tolerance each contact assembly is preferablyindividually adjustable. To accomplish this a side plate 84 having adeformable finger 86 for each contact assembly is secured to the movablearmature 52. These fingers are offset from the end of armature 52 andslidably fit in the openings 44 of the plungers 28. When such armatureis held against movement each plunger can be separately moved to bendits finger to the position affording the desired wear allowance.

To set the contacts for a wear allowance within the range from .053-.059inch, a gage having a thickness of .O53 inch is placed between themovable armature 52 and the magnet frame 56. Coil 54 is energized tolock the armature. The deformable fingers 86 having been roughly set sothat there is no contact between bridging contactors 22 and xed contacts20 under these conditions, are each separately bent by pushing eachbridging contactor into contact with the stationary contacts. The pointat which contact is made can be accurately determined by a test lampconnected across the fixed contacts. After this adjusting operation iscompleted the .053 inch gage is removed and a .059 inch gage is insertedin its place and the coil S4 is again energized. If the test lamp failsto light then the contact assembly so tested is properly adjusted andfalls within the desired range. However, if the lamp lights, `suchcontact assembly is too tight and the fingers 86 should be bent byslightly pulling the plunger 28 of such assembly. A recheck of thisassembly with the .053 gage must then be made.

The assembly of the switch may be accomplished by placing the plungers28 in the openings 42 of the dividing wall with the openings 44 lyingbeneath the notches 60. The armature S2 is then slid in between thewalls 50 while raised in the notches 60 until the fingers 86 are alignedwith the openings 44. The armature may then be lowered to normalposition and moved into engagement with the projections 64. The bridgingcontactors 22, springs 30 and cups 32 can now be assembled. Thereafterthe return springs 78, coil 54, magnet frame 56 and mounting plate 12are assembled in that order. No fastenings are required except for themounting plate l2 which holds the parts in operating position.

When the coil 54 is energized the parts move from the positions shown inFig. 2 to the positions shown in Fig. 3. During such movement thecontacts are engaged and the springs 30 and 7S compressed. Therelatively light magnet frame 56 freely rocks on the convex surfaces 76and makes flush contact with the armature 52. The positioning of thecoil 54 by reason of the magnetic field is substantially neutralized andonly the light force of springs 78 urges the coil toward the magnetframe. Hence, all parts are easily aligned and maximum holding forcedeveloped while enjoying quiet operation.

The momentum imparted to the heavy armature 52 carries it through thecritical oscillatory point near its engagement with the magnet frame.

We claim:

l. An electric control device comprising in combination, an insulatinghousing having a recess with abutrnents adjacent the open end thereof,stationary contacts mounted in said housing, a bridging contactor forsaid stationary contacts, a movable armature in said recess, meansconnecting said armature to said bridging contactor, an electromagneticcoil having an end plate loosely mounted in said recess and resting onsaid abutments, a magnet frame resting on said housing adjacent saidcoil and loosely holding said coil with said plate on said abutments topermit said `coil to move slightly in all directions, said plate havingspring engaging portions, means removably secured to said housing forholding said magnet frame on said housing, and spring means in saidrecess between said spring engaging portions and movable armature tomove said movable armature to open contact position upon de-energizationof said coil.

2. An electromagnetically operated switch comprising an insulatingsupport having side walls interconnected by a dividing wall having anouter side and an inner side, fixed contacts on the outer side of saiddividing wall, an opening in said dividing wall, an insulating slidermounted in said opening and extending on both sides of said dividingwall, a movable contactor carried by said slider and engageable withsaid fixed contacts, protecting walls extending between said side wallsand projecting from the inner side of said dividing wall to form arecess, guides integral with said protecting walls, a movable armatureguided in said recess by said guides and connected to said insulatingslider, an induction coil loosely seated in the opening to said recessin operative relationship to said armature, compression springs in saidrecess having one end seated on the end of said coil and operablebetween said coil and said armature, and a magnet frame removablymounted in said side walls and loosely holding said coil in place.

3. An electric control device comprising an insulating support, astationary contact on said support, a movable contact cooperable withsaid stationary contact, a movable armature guided by said support, anelectromagnetic coil mounted on said suppont and having an opening, saidarmature having three legs as long as said coil with the 5 center legoperating within said opening, said armature having brackets injuxtaposition with the end of said coil,

a magnet frame carried by said support, and coiled compression springsseated on the end of said coil and engaging said brackets to return saidmovable armature to del0 energized position.

References Cited in the file of this patent UNITED STATES PATENTS Wilmset a1. Nov. 20, Schmitt Dec. 6, Rosing et al. Nov. 4, Van ValkenburgJuly 4, Charbonneau et al. Apr. 29, Scheib Oct. 28,

